1. Field of the Invention
The present invention relates to a communication slave used in a communication network system configured by coupling a master and a plurality of communication slaves through a pair of buses in a daisy-chain manner. The present invention also relates to the communication network system.
2. Description of the Related Art
A protocol of a communication network including a master and a plurality of slaves coupled through a pair of buses in a daisy-chain manner includes a DSI (distributed system interface) and a SbW (safe by wire). The communication network needs to set an ID to each of the slaves so that the master can perform a serial communication with the slaves. For example, JP-A-2003-152741 (corresponding to US 2003/0034883 A1) discloses a communication apparatus in which each of plurality of slave devices inserts a switch into a power source line that forms a bus a master device sets IDs of the slaves through the bus in order from the slave device close to the master device based on a connection order of the slaves and IDs stored in the master device, and the slave device whose ID is set turns on the switch one by one so that a next slave is coupled with the bus.
When the switch is inserted into the bus, an element such as a transistor for forming the switch needs to reduce an on-resistance value. Accordingly, a dimension of the switch may be increased, and a dimension of each of the slave, eventually, a dimension of the whole communication network system may be increased.